<?php

require_once 'HTMLPurifier/AttrDef.php';
require_once 'HTMLPurifier/AttrDef/URI/IPv4.php';
require_once 'HTMLPurifier/AttrDef/URI/IPv6.php';

/**
 * Validates a host according to the IPv4, IPv6 and DNS (future) specifications.
 */
class HTMLPurifier_AttrDef_URI_Host extends HTMLPurifier_AttrDef
{
	
	/**
	 * Instance of HTMLPurifier_AttrDef_URI_IPv4 sub-validator
	 */
	var $ipv4;
	
	/**
	 * Instance of HTMLPurifier_AttrDef_URI_IPv6 sub-validator
	 */
	var $ipv6;
	
	function HTMLPurifier_AttrDef_URI_Host() {
		$this->ipv4 = new HTMLPurifier_AttrDef_URI_IPv4();
		$this->ipv6 = new HTMLPurifier_AttrDef_URI_IPv6();
	}
	
	function validate($string, $config, &$context) {
		$length = strlen($string);
		if ($string === '') return '';
		if ($length > 1 && $string[0] === '[' && $string[$length-1] === ']') {
			//IPv6
			$ip = substr($string, 1, $length - 2);
			$valid = $this->ipv6->validate($ip, $config, $context);
			if ($valid === false) return false;
			return '['. $valid . ']';
		}
		
		// need to do checks on unusual encodings too
		$ipv4 = $this->ipv4->validate($string, $config, $context);
		if ($ipv4 !== false) return $ipv4;
		
		// A regular domain name.
		
		// This breaks I18N domain names, but we don't have proper IRI support,
		// so force users to insert Punycode. If there's complaining we'll 
		// try to fix things into an international friendly form.
		
		// The productions describing this are:
		$a   = '[a-z]';	 // alpha
		$an  = '[a-z0-9]';  // alphanum
		$and = '[a-z0-9-]'; // alphanum | "-"
		// domainlabel = alphanum | alphanum *( alphanum | "-" ) alphanum
		$domainlabel   = "$an($and*$an)?";
		// toplabel	= alpha | alpha *( alphanum | "-" ) alphanum
		$toplabel	  = "$a($and*$an)?";
		// hostname	= *( domainlabel "." ) toplabel [ "." ]
		$match = preg_match("/^($domainlabel\.)*$toplabel\.?$/i", $string);
		if (!$match) return false;
		
		return $string;
	}
	
}

